Re: [PATCH RFC 1/3] lib: add talloc for overlaying a tree onto allocations

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Sascha,

On 11/7/25 2:55 PM, Sascha Hauer wrote:
> On Tue, Oct 28, 2025 at 11:26:02AM +0100, Ahmad Fatoum wrote:
>> Hi,
>>
>> On 10/28/25 10:42 AM, Sascha Hauer wrote:
>>> On Mon, Oct 27, 2025 at 08:54:32AM +0100, Ahmad Fatoum wrote:
>>>> +#ifndef __TALLOC_H__
>>>> +#define __TALLOC_H__
>>>> +
>>>> +#include <linux/types.h>
>>>> +
>>>> +struct talloc {
>>>> +	struct talloc *child;
>>>> +	struct talloc *next;
>>>> +	union {
>>>> +		struct talloc *prev;
>>>> +		struct talloc *parent; /* Valid only when is_first(mem) */
>>>> +	};
>>>> +};
>>>
>>> Currently tlsf allocations are 8 byte aligned. On 32bit architectures
>>> struct talloc will be 12 bytes, so talloc allocations will only have 4
>>> byte alignment.
>>
>> Good catch. On 32-bit, there is 4 bytes of unused padding inside TLSF
>> and feels bad sacrificing 4 more bytes here. :/
> 
> I find the memory leak checker extremly useful and it becomes even more
> useful with the memory leaks in hush fixed.
> 
> I suggest we add an __aligned(8) here and be done with it for now.
> 
> We can still think about it when widening the talloc use for
> dev_kmalloc(), but as long as it's only used by hush we shouldn't hold
> this series up.

Fair enough.

Thanks,
Ahmad

> 
> Sascha
> 

-- 
Pengutronix e.K.                  |                             |
Steuerwalder Str. 21              | http://www.pengutronix.de/  |
31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |